Thanks. Some small suggested changes:

1. Specify endianness of the each field. In your examples, the prefix is big-endian, but the date is little-endian. I recommend big-endian for all fields (since in many scripting languages, it's easier to go from an integer to a big-endian string than a little-endian string).

2. Recommend that client implementers check the blockchain, say, a day before the beginning of the "recorded" date to account for slightly incorrect date calculations. Either that or specify that the date code should be based on date minus one day.